Dilation catheters are used for opening blood vessels or other passageways in the body that may be blocked by obstructions or stenosis. Dilatation catheters are generally formed from thin, flexible tubing having an inflatable balloon at or near a distal tip of the catheter that can be inflated with fluid pressure communicated to the balloon through a lumen of the catheter. In a typical angioplasty procedure, the balloon dilatation catheter is passed through the vasculature to the location of a stenosis in an artery, and the balloon is inflated to a predetermined size and shape to open the blocked artery.
It is desirable for balloons of balloon dilatation catheters to be capable of inflating to a diameter of typically many times their uninflated diameter in order to be able to open an obstructed vessel. Other desirable properties of balloons for such balloon dilatation catheters include strength, softness, flexibility and a thin, low profile which are important for achieving the performance characteristics of folding in an uninflated state, tracking, crossing and recrossing the area of the obstruction or stenosis in a vessel in an uninflated state. In addition, properties of burst strength, compliance, and fatigue have been increasingly important in the continuing effort to create thinner, lower profile balloons for dilatation catheters with an ability to track, cross and recross increasingly narrow passages in obstructed vessels.
Polymeric materials that have been used for making medical devices, catheters, dilatation catheters, and balloons for dilatation catheters include polyethylene, polyolefins, polyvinyl chloride, polyester, polyamide, polyethylene terephthalate (PET), polyamides, polyurethane, and the like. Balloons made of soft polyolefin or ethylene copolymers materials are typically foldable, and track and cross well, so that they can often be used more than once, and can be used to cross multiple lesions. However, such balloons also commonly have high balloon compliance and low burst strengths. Balloons made from polyethylene terephthalate (PET) are commonly stronger, with a higher rated burst pressure. However, dilatation catheter balloons made of PET are generally stiff, not readily foldable and refoldable, and are susceptible to acquiring defects from mechanical handling.
It would be desirable to provide a polymeric blend for balloons of balloon dilatation catheters with a combination of the best features of the softer balloon materials and the stronger balloon materials, including good flexibility, folding, track, cross and recross, with a thin, low profile, high resistance to fatigue, low compliance, and high burst strength.